The present invention relates generally to the rotor element of fluid control valves or a rotor used with an actuator. In particular, it relates to the rotor element of electrically actuated valves of the type utilized in internal combustion engines as governors to throttle the flow of fuel so as to moderate fuel pressure.
In internal combustion engines, and in manufacturing such as chemical processing, it is often necessary to control fluids flowing through lines of 0.98 to 0.787 cm in diameter. The fluids traversing these lines flow at a relatively fast rate. Due to the nature of the end process of the fluid, it is sometimes necessary to change the fluid flow rate, often from full on to full off, at rapid rates, over a sustained period of time.
Valves have been designed which are able to control fluid flow, by opening and closing their orifices, and which are able to withstand the wear of vigorous use. One such valve was disclosed in U.S. Pat. No. 4,339,737 to Meyers and Glynn. This valve comprises a rotor having a magnetically actuated rotor body housed in a stator with a coil means, and a hollow rotor stem housed in a valve sleeve. The rotor body-rotor stem is a one piece unit. The rotor stem and the valve sleeve each have a pair of symmetrical ports, which when aligned allow unrestricted fluid flow. The valve is inserted into the body of a fuel pump so the valve sleeve and rotor stem are located in the cavity of the pump. Within the cavity the fuel is under pressure so that when the ports on the rotor stem and valve sleeve are aligned fuel is forced through the rotor stem and out the valve sleeve through lines connected thereto. Energizing the stator coil attracts the magnetic poles on the rotor, causing it to turn. The movement of the rotor causes the orifice formed by the two sets of ports to change size, thus controlling the flow rate of fluid flowing through the valve. Through the use of magnets, guides, and springs, the rotor turns at a constant rate, turns only through a defined arc, and returns to its original position when the stator coil is deenergized. An additional feature of this device is a rotor stem extending below the valve ports. This rotor stem, resting in the valve sleeve, serves to stabilize the rotor as it turns.
One disadvantage of the valves of this type is that they are affected by stress from liquid in the pump cavity. The liquid in the pump cavity is under changing pressure thus causing the stress. Stress may also be caused by mechanical variations due to machining tolerances or by misalignment due to poor installation practices. These stresses subject the valve sleeve with rotor stem therein to lateral forces, causing the valve sleeve to bend. The bending of the valve sleeve may cause the rotor stem to bend, forcing it out of alignment. Such bending may also serve to reduce the lifespan of the valve.
Thus it is an object of this invention to provide a rotor of such design so as to flex within the valve sleeve so that the complementary parts will stay aligned and the efficiency of the valve will be maintained. A further advantage of this design is that wear on the rotor will be reduced increasing the useful life of the valve.
In systems known to the applicant, the manufacture of such valves is difficult. This is in part because the various valve elements are of relatively small size; stators are 1.969-3.937 cm high, and at their smallest, may be 0.787-1.575 cm across. The rotor stem required to fit inside the sleeve is, of course, smaller; it may be 1.575-2.756 cm high and at its smallest 0.098-0.591 cm in diameter. Because the various valve parts are required to be precisely aligned, the parts must be installed precisely. As a result, the cost of manufacturing these valves is relatively high.
Hence, it is an additional object of this invention to provide a valve rotor of such design that it can be inserted into the valve sleeve without precision alignment and will function properly.